Suppose xA $=1\mathrm{.}8179,$ yA $=0\mathrm{.}394($in decimal format$)$ are correctly rounded to the number of digits shown $($by rounding to the nearest numbers$).$ For each calculation, determine the smallest interval in which the result, using true instead of rounded values, must lie.

$1.$ xA $+$ yA

$2.$ xA $\backslash$times yA